| abstract |
A drilling fluid composition comprising a base fluid, and a viscosifier including an ultra-high molecular weight branched block copolymer having the following structure, n n n n n n n n n n where monomer A is an anionic monomer, monomer B is a hydrophilic monomer, monomer C is an anionic monomer, monomer D is a crosslinker-divinyl monomer, and —SSCZ ground being a terminal RAFT agent. |